Oil well formation tester



June 13, 1950 P. S.'WILLIAMS OIL WELL FORMATION TESTER Filed April 23,1948 MMQSQI 5 m 1 O 2 o .1 M KE/ m M @Q 0 P w 1 ELL phtltj: 6. wflziams(Savant/or" Patented June 13, 1 950 ration of Delaware Standard OilDevelopment Company, 'a, corpo- Application Am 23, 1948, Serial No.22,922

6 Claims. 1 (G1. 1.66?!) The present invention relates to an improvedtype of formation tester to be employed in oil;

wells. In accordance with this invention an apparatus is provided havinga, motor operated to work pumping means associated with an inflatablepacker and a sample containing chamber, to permit sealing off a desiredportion of an oil well and to permit withdrawing fluid from this portionof the well into the sample chamber.

In drilling an oil well, the well is maintained full of a fluid such asdrilling mud. This is necessary in order to maintain a sufiiciently highhydrostatic pressure in the well to prevent the uncontrolled escape ofnatural fluids in the earth. However, the necessity for maintaining thewell full of fluid during the drilling complicates the removal ofnatural fluids from the earth for sampling purposes. Thus, in order toremove a sample of fluid from a particular stratum of the oil well, itis first necessary to reduce the hydrostatic pressure of drilling mud onthis stratum sufficiently to allow the escapeof the fluid from thestratum and then in some way .to remove the fluid extracted to thesurface of the earth. The technique by which this is done is calledformation testing and the apparatus employed for the purpose is calledformation testing apparatus. It is this field with which the presentinvention is concerned.

Formation testing apparatus has been proposed of such a nature that aninflatable elastic packer is used to seal off the well at a desiredpoint so as to permit reducing the hydrostatic pressure at the pointsealed off without reducing the hydrostatic pressure throughout thewell. However, an apparatus of this type presently known to the art isof rather complicated construction and is not flexible in the sense thatit cannot be used under a variety of conditions. For example, it ispresently necessary to employ one type of formation tester incombination with a drill string or to employ a difierent type of testerin combination with a coring bit or even to employ a testernecessitating removal of all drilling apparatus from the well.Therefore, it is a principal object of this invention to provide animproved form of elastic packer formation tester which may be used underany of the circumstances indicated above.

In accordance with this invention a compact packing means associatedwith suitablepumpingv means so as to permit sealing off the well at anydesired point and so as to permit pumping samples of fluid through aporous section of the elastic packer to a suitable sample-receivingchamher, The apparatus may be supported by a cable or by the drill.string. As indicated, therefore, the apparatus of this invention ischaracteriz ed by simplicity of construction, flexibility of: use, andease of sampling.

A preferredform of the apparatusof the present invention is illustratedin the attached Figs. 1, and 2. These figures are related as Fig. 1 issimply the upper continuation of Fig. 2. In these figures, the numeral lidentifies a well hole which has been dug in the earth. It is to beunderstood that this hole is normally filled with fluid such as drillingmud. For simplicity no fluid has be n shown inthe drawings in the holeI. The apparatus illustrated is suitably supported in the hole by meanssuch as the cable 2. As will become apparent, in place of the cable '2,a drill string or equivalent supporting means may be employed. The cable2 is of the conventional type suitable for sustaining the weight of theapparatus and at the same time suitable for protecting. electricalconductors contained in the cable. In the drawing, the cable 2 is shownto be terminated by a sample-receiving chamber indicated by the numeral9. This sample chamber supported by the cable 2 serves in turn tosupport the remaining components of the apparatus. Thus a connectingmember or support is provided to connect the sample chamber 9 with themotor 25. The motor 25 in turn is connected to the pump 1 by theconnecting and supporting means indicated as rods 26. Similarly, asecond pump I5 is connected to pump I by supporting means 21 and thepump I5 is connected to the elastic packer by the supporting rod 28. Asillustrated, the motor 25 is an electric motor suitably supplied withelectricity through a conductor leading from the cable 2, either throughor around the sample chamber 9. The motor 25, is, directly connected tothe pumps 1 and i5 through shaft 29. The elastic packer indicated by thenumeral 3, as illustrated in the inflated position, is essentially anoval-shaped bag. It will be noted that a portion of the bag, comprisinga narrow. circumference, consists of a double walled space identified bythe numeral 5 I. While all portions of the packer except thecircumference of the double walled portion of the packer are ofnon-porous material, the portion of the packer comprising the.circumference bounding the space BI is of porous material. This poroussection of the packer is indicated by the numeral 52.- In fabricating apacker such as that illustrated, it is convenient to employ rubber, alithough cloth or wire fabric may be employed if desired. Similarly, theporous section of the packer, that is, section 52 may comprise a poroustype of rubber. Suitable porous rubber is now commercially available. Inthe event that the porous section of the packer 52 and the remainder ofthe packer is made of rubber, the fabrication of the packer is quitesimple. The

inner portion of the double walled space indible packer having a portionof thepacker made i as a double walled section. The exterior of thepacker comprising the outer surface of the double walled section isporous, while the other parts of the packer are non-porous. It isapparent that fluids may be allowed to enter the double walled sectionof the packer through the outer porous circumference of the packer.Positioned in the double walled section of the packer are a multitude ofpellets indicated by the numeral 5. These pellets may consist of glass,metal, rock or any other desired substance. As will become apparent, thefunction of these pellets is to fill the double walled section of thepacker so that this section cannot be compressed suificiently' to sealit. Thus, the presence of the pellets in the double walled sectioncontinuously maintains a porous medium in the packer. It is apparent, ofcourse, that the pellets should be of sufficient size so that they donot pass out of the perforations of the porous area-52 of the packer. Aconduit 54, porously sealed to prevent passage of the pellets, isprovided to connect the double walled section of the packer with theinlet of pump 7. The outlet of this pump is connected with line 55 whichleads to the sample chamber 9. Thus, the operation of pump 1 will tendto cause fluid to be pulled through the perforations of layer 52 of thepacker through the double walled section of the packer and conduits 54and 55 into the sample chamber. A conduit I1, is also providedconnecting the innermost part of the elastic packer to the outlet ofpump I5. The inlet of pump i is connected to the conduit or port It,which opens into the well. Consequently by operation of pump l5, fluidwill be pulled from the well through conduits l6 and I1 into the elasticpacker, serving to inflate the packer.

The apparatus heretofore described is complete except for the provisionof necessary valves in the various chambers. Thus it is necessary that avalve l0 and a valve H be positioned in the sample chamber. The valve I0is operative to seal the inlet into the sample chamber served by- Thus,the operation of these valves is controlled by current supplied throughthe conductors at the surface of the earth.

The apparatus illustrated in Figs. 1 and 2 having now been suitablyidentified and described,

the operation of this apparatus may be fullyunderstood.

By conventional drilling p f0cedures, a suitable bore hole is drilled inthe earth. During the drilling operation by various, conventional typesof logging, the nature of strata through which Valvethe hole passes areidentified. These logging procedures are generally suitable forindicating possible strata suitable for oil production. One such stratumsuch as the porous zone 4, is illustrated in the drawing. In order totest the fluids, if any, present in this porous formation, the apparatusof this invention is then employed. In the event that a drill stringhaving a core bit has been used to drill the hole, the apparatus may belowered through the drill string and through the core bit; the core bit,of course, being pulled up from the bottpm of the well sufficiently tobe above the porous formation to be tested. Alternatively, the drillstring and drilling apparatus may be completely removed from the hole.In any event, the apparatus illustrated in Figs. 1 and 2 is lowered intothe well so that the double walled section of the packer is adjacent tothe porous formation to be tested. While the apparatus is being lowered,the elastic packer is in the deflated position making the packer and theassociated equipment sufficiently compact to readily pass downwardlythrough the drill string or down the well. When the apparatus has beenlowered suificiently so that the double walled section of the packer isadjacent the porous formation to be tested, the packer is inflated bystarting the motor 25. At the same time the motor is started, valves l0and II are opened by operation of suitable electrical circuits at thesurface of the earth. Inactual practice, it is convenient to have thesolenoid valves Ill and II connected in either series or parallel withthe electrical circuit of the motor 25. In this case, it ispossible tostart the motor and to open valves H1 and H by closing a singleoperating switch at the surface of the earth. For simplicity, thesecircuits are not shown on the drawings as the circuits themselves do notconstitute part of this invention andsince they are conventional, simplycomprising a suitable switch, a voltage source, and the necessaryelectrical connections. While pumps I and I5 maybe either centrifugalpumps or positive displacement pumps, let it be assumed nowthat pump i5is a centrifugal pump. The operation of motor 25 will cause both pumpsto operate. Pump l5 will draw fluid from the Well through port l6 andwill pump this fluid through line H into the elastic packer causing thepacker tobeinflated. Simultaneously pump T will tend to pull fluidthrough the perforations of layer 52 of the packer through line 54. Thisfluid will be pumped through line 55 into the sample chamber throughvalve l0 and out of the sample chamber through valve H. The pumpingaction ofpump I5 will continue until sufficient fluid has been pumpedinto the elastic packer to fully expand it, (i. e. the pump I5 is sochosen that the maximum pressure which it will deliver is such as toproperly inflate the packer), thoroughly sealing the well hole adjacentto the packer. This will cause the double walled section of the packerto be tightly forced against the porous formation 4. Therefore, theaction of the pump 1 will pull fluid from the porous formation throughline 54 and 55 into the sample chamber. The pumping action is continueduntil the setting of the packer is assured and until sufficient time hasbeen allowed for fluid to have filled the sample chamber 9. If desired,an auxiliary electrical device 40, may be placed in line 55 to check thenature of the fluid passing through this line. Suitable indicatingdevices, for example, a resistivity indicator, will give electricalindications at the surface of the earth, through conductors which maypass through cable 2, of the conductivity of the fluid in line 55. Bythis means it is possible to insure that the fiuid passing through line55 is not simply drilling mud obtained from the well, but is fluidextracted from the porous formation 4. When the pumping operationdescribed has been continued until a suitable sample has been 'receivedin the sample chamber 9, the motor 25 is stopped and the valves and IIare closed. Again, if desired, these operations may be completed byopening a single switch at the surface of the earth. Stopping the motor25, will permit the fluid contained in the elastic packer to passthrough line H, through centrifugal pump "I5, and out through the port18 to deflate the packer. The entire apparatus may then be drawn to thesurface of the earth and the sample in sample chamber l3 can be examinedas desired.

As indicated, if desired, pump is as well as pump 1 may consist of apositive displacement instead of a centrifugal pump. In the event Pumpi5 is a positive displacement pump, it is necessary to include twofurther valves in the system. These are valves I8 and 20, located inline 11. Valve 18 is a simple check valve, spring loaded to be opened ata given pressure. The valve is adjusted so that this pressure issuflicient to insure full inflation of the elastic packer, but isinsufiicient to permit rupture of the elastic packer. Thus on operationof the pump l5, fluid will be pumped into the elastic packer until thepacker is fully inflated, at which time the pressure in the system willbe suificient to open the relief valve [8. This will permit fluid pumpedby pump 15 to bleed oil into the well without permitting the packer todeflate. After the sampling operation has been completed, in order todeflate the packer, it is then necessary to open valve 20 in line 11.Valve 20 may again comprise a solenoid operated valve which may" besuitably controlled at the surface of the earth by means of conductorspassing through the cable '2. For the purpose of simplicity, theseconductors have not been illustrated in the drawing. Again, if desiredthe valve 20 may be connected in an electrical circuit with valves inand II and the motor 25 so that on closure of a single switch, the motor25 will be started and valves l0 and II will be opened and valve 20 willbe closed. Alternatively, when the single switch is opened, the motor 25is stopped and valves 10 and II are closed and valve 20 is opened.

As indicated above, the apparatus illustrated is subject to manyrefinements and many-modifications. An important refinement which maybe, or should be, used is the provision of a channel 22 which passesdownwardly through the elastic packer to provide a fluid chamber fromthe space above the packer to the space below the packer. The functionof this passageway is to permit equalization of pressure above and belowthe packer so that no vertical component of pressure is exerted on theelastic packer.

A further modification of importance is to substitute for the cable 2and the sample chamber 9, a drill string. In this event, the drillstring will serve as both a supporting means for the apparatus and as asample receiving chamber. The line will then pass directly into thedrill string without necessity for valves III or I I. The support 50holding the motor may be connected to the drill string by means of asimple pipe cap which may be threaded on to the drill string.

On operation of the pump 25, therefore, fluid will be withdrawn from theporous formation 4 and will be pumped into the drill string toward;

the surface of the earth. In this event it will be string.

It should also be noted, that the apparatus 1 illustrated in the drawingis diagrammaticjanjd is presented solely to illustrate the nature ofthis invention. sample chamber or a drill string is closely? coupled tothe motor, the pumps, and the elastic packer, so as to provide anintegral apparatus extremely compact and comparatively light in Inactual construction,- the weight.

In view of the many modifications of the present invention, the appendedclaims are to be interpreted broadly, limited only by the truecontribution to the art:

What is claimed is:

1. A well testing apparatus for use in a fluidfllled borehole comprisingin combination a suppotring means provided with a sample-receivingchamber, an inflatable elastic bag fixed to said supporting means, thewalls of said elasticbag being constructed of non-porous flexible ma- 7terial, a porous wall attached circumferentially to the exterior of saidelastic bag about a middle portion thereof and defining an annularchamber with a portion of the wall of said has. a first pumping meansand a second pumping means carried by said supporting means, a firstconduit connecting said annular chamber through said first pumping meansto said sample-receiving chamber, and a second conduit connecting theinterior of said elastic bag to said second pumping means. saidlast-named pumping means having an inlet port communicating with saidfluid in the borehole.

2. Apparatus as defined in claim 1 in which said supporting meanscomprises a section of drill pipe whose interior constitutes saidsamplereceiving chamber.

3. Apparatus as defined by claim 1 in which said sample-receivingchamber is provided with an inlet valve associated with said firstconduit and an outlet valve having a port communicating with said fluidin the borehole.

4. Apparatus as defined by claim 1 in which said annular chambercontains pelleted packing material.

5. Apparatus as defined by claim 1 including a channel passing throughsaid elastic bag and communicating with said fluid in the borehole aboveand below said bag.

6. Apparatus as defined by claim 1 in which said second conduit isprovided with a pressure relief valve adapted to vent fluid into saidborehole upon attainment of a predetermined pressure within saidconduit.

PHILIP S. WE-LIAMB.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 602,547 vTitus Apr. 19, 18982,404,825 Brown July 30. 1946 2,441,894 Mennecier May 18, 1948

